The present invention relates to a torque transmitting member that is used in an image forming apparatus, such as a laser printer or a copy machine, a photosensitive drum unit that includes the torque transmitting member, and a process cartridge.
An image forming apparatus, such as a laser printer or a copy machine, is provided with a process cartridge that can be mounted on and separated from an image forming apparatus body (hereinafter, referred to as an “apparatus body”).
The process cartridge is a member that forms contents to be shown, such as letters and figures, at a posture where the process cartridge is mounted on the apparatus body and transfers the contents to a recording medium such as paper. For this reason, the process cartridge is provided with a photosensitive drum on which contents to be transferred are formed and means (charging means and developing means) for forming the contents to be transferred to the photosensitive drum.
The same process cartridge as the process cartridge is mounted on and separated from the apparatus body for the purpose of maintenance, or an old process cartridge is separated from the apparatus body and a new process cartridge is mounted on the apparatus body for the replacement of the old process cartridge with a new process cartridge. Since the mounting and separation of the process cartridge are performed by a user of the image forming apparatus, it is preferable that the mounting and separation of the process cartridge can be easily performed as much as possible from such a point of view.
Incidentally, the photosensitive drum included in the process cartridge needs to be rotated when being operated. Further, the photosensitive drum is provided with a bearing member, and the bearing member is directly engaged with a rotary drive shaft of the apparatus body or is engaged with the rotary drive shaft through other members. Accordingly, the photosensitive drum receives torque from the drive shaft and rotates.
Meanwhile, in order to mount and separate the process cartridge on and from the apparatus body as described above, it is necessary to disengage (separate) the drive shaft of the apparatus body from the bearing member of the photosensitive drum and to engage the drive shaft with the bearing member again each time.
In addition, since the photosensitive drum is charged by a voltage applied from the apparatus body through the charging roller and develops an image to be formed by this charged state, charging and the elimination of electricity are performed as necessary in the respective processes for forming and transferring the image. The photosensitive drum is electrically conducted to the apparatus body at the time of the elimination of electricity, so that grounding is achieved.
Patent Documents 1 and 2 disclose an aspect that includes a ground plate (sheet metal plate) as means (conducting means) for electrically conducting a photosensitive drum to an apparatus body. The ground plate is disposed in the photosensitive drum so as to close the inner portion of the photosensitive drum, and is a conductive plate-like member formed so that at least a part of the outer peripheral portion of the ground plate comes into contact with the inner peripheral surface of the photosensitive drum.
In Patent Document 1, a conductive shaft, which extends from the apparatus body passing through a flange (end member) and inserted into the photosensitive drum, can conduct electricity by coming into contact with contact pieces of the ground plate. In this case, the contact pieces are formed so as to be capable of being elastically deformed in the form of a leaf spring.
In Patent Document 2, a conducting shaft, which comes into electrical contact with the ground plate, is enclosed in an end member and the conducting shaft can conduct electricity by coming into contact with a conductive pin of the image forming apparatus. Here, a technique in which a contact point of the apparatus body is rotated and moved in an axial direction and always comes into contact with the same contact point to suppress the occurrence of conduction failure is disclosed in order to stabilize the conduction between the apparatus body and the photosensitive drum.